WordNet (r) 3.0 (2006):

fixer
    n 1: someone who intervenes with authorities for a person in
         trouble (usually using underhand or illegal methods for a
         fee) [syn: fixer, influence peddler]
    2: a chemical compound that sets or fixes something (as a dye or
       a photographic image) [syn: fixing agent, fixer]
    3: a skilled worker who mends or repairs things [syn: mender,
       repairer, fixer]
    4: synthetic narcotic drug similar to morphine but less habit-
       forming; used in narcotic detoxification and maintenance of
       heroin addiction [syn: methadone, methadone
       hydrochloride, methadon, dolophine hydrochloride,
       fixer, synthetic heroin]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "fixer":
   cobbler, developer, doctor, five-percenter, fixing bath,
   four-percenter, hypo, influence peddler, little Miss Fixit,
   logroller, maintenance man, mechanic, mechanician, mender,
   power broker, processing solution, renovator, repairer, repairman,
   restorer, serviceman, short-stop, short-stop bath,
   sodium hyposulfite, sodium thiosulfate, soup, stop bath, tinker,
   trouble man, troubleshooter, wire-puller